1. Field
The present disclosure relates generally to communication systems, and more particularly, to supporting device-to-device communication within a long term evolution (LTE) based network while minimizing Request-To-Send/Clear-To-Send (RTS/CTS) signaling overhead resource usage.
2. Background
Wireless communication systems are widely deployed to provide various telecommunication services such as telephony, video, data, messaging, and broadcasts. Typical wireless communication systems may employ multiple-access technologies capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power). Examples of such multiple-access technologies include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, single-carrier frequency division multiple access (SC-FDMA) systems, and time division synchronous code division multiple access (TD-SCDMA) systems.
These multiple access technologies have been adopted in various telecommunication standards to provide a common protocol that enables different wireless devices to communicate on a municipal, national, regional, and even global level. An example of a telecommunication standard is Long Term Evolution (LTE). LTE is a set of enhancements to the Universal Mobile Telecommunications System (UMTS) mobile standard promulgated by Third Generation Partnership Project (3GPP). LTE is designed to better support mobile broadband Internet access by improving spectral efficiency, lower costs, improve services, make use of new spectrum, and better integrate with other open standards using OFDMA on the downlink (DL), SC-FDMA on the uplink (UL), and multiple-input multiple-output (MIMO) antenna technology. LTE may support direct device-to-device (peer-to-peer) communication (e.g., LTE-Direct).
Currently, an aspect of supporting device to device (D2D) communications in an LTE environment (e.g., LTE-Direct) is use of distributed scheduling. Distributed scheduling refers to the mechanism of coordinating, in a distributed way, the D2D transmissions of different links without incurring excessive interference among them. This can be done through RTS/CTS handshake signaling before the DATA transmissions. In LTE-Direct, there is a RTS block and a CTS block before each phase of DATA transmissions. In an aspect, there may be 24 resource blocks (RBs) in the RTS block (and in the CTS block). Each D2D link may use a pair of RBs in the same location in the RTS block and CTS block, which we refer to as a connection ID (CID) resource, for RTS/CTS transmissions. As such, each link may use a sequence (e.g., a Zadoff-Chu sequence) in the RTS/CTS transmissions, and an RTS/CTS can be decoded successfully if its signal to interference ratio (SIR) is above a threshold. Minimizing RTS/CTS overhead helps to achieve high throughput of D2D communications. This overhead can become significant in terms of time frequency resources used for RTS/CTS signaling.
As the demand for device-to-device communication increases, there exists a need for methods/apparatuses for supporting device-to-device communication within LTE while minimizing RTS/CTS signaling overhead resource usage.